Why Michael Phelps has those weird shoulder marks

Yesterday saw the American men's 4x100 metre freestyle team take home the gold in a dominant display – but as they got out of the pool, much of the attention turned to Michael Phelps's shoulders.

Not for their impressive size, mind you – but because they were covered in perfectly circular bruises, the result of an ancient practice called "cupping".

While it looks like the work of aliens (or as one Twitter user described, "fake hickeys"), cupping dates back as far 6500 years ago in rural China and was pushed into the mainstream more than a decade ago by Gwyneth Paltrow.

(Image: Vaughn Ridley/Getty Images)

Essentially, cupping involves heating up small glass cups and placing them on somebody's body. This creates a small vacuum which sucks the skin up into the cup, drawing blood to the surface. Sometimes a small pump is connected to the cups, to help draw the skin even further up.

As the theory goes, this enables blood to flow better throughout the body, getting rid of toxins and speeding up recovery.

If you've ever put your mouth over the tube of a vacuum cleaner and felt the blood pool into your lips, it's essentially the same process at work. (Just me?)

Cupping has been a part of Phelps's training routine for over two years, and gives him a psychological boost when recovering from particularly hard-fought races.

"So I asked for a little cupping yesterday because I was sore and the trainer hit me pretty hard and left a couple of bruises."

Phelps's personal trainer Keenan Robinson believes there's real benefits for athletes who are performing at the top level.

"[Cupping] is just another recovery modality. There’s nothing really particularly special about it," Robinson told the New York Times.

"Anything you can do to get the body to feel good — you have to use an educational assessment on it. You have to make sure that what you’re doing is causing a physiological intent to recover."

So does cupping actually work – or is it yet another tool that the average weekend warrior has no business concerning themselves with? At present, the science is fairly divided.

In 2012 researchers from China performed a systematic review of every bit of research ever undertaken on cupping. After looking at over 100 randomised controlled trials, the researchers were just as confused as we are now – arguing that cupping may work for some things, but the evidence is poor.

"Our review showed that cupping has potential effect in the treatment of herpes zoster and other specific conditions," wrote the study's author, Huijuan Cao.

"However, further rigorously designed trials on its use for other conditions are warranted."

"Cupping is a predominantly safe technique," Dripps tells Coach. "There isn't strong evidence for – or against – cupping, and what may work for some people won't work for others."

"If we think broadly about some of the recovery techniques these athletes are using – you've got to start with the premise that they're pushing their bodies to the absolute limit every time they train or compete."

According to Dripps, because cupping stems from traditional Chinese medicine, there's a lot of fluff that surrounds it — but that doesn’t mean we should write it off straight away.

"As with a lot of these things, at first glance it appears a bit wacky. As a physiotherapist, the first thing you have to do with any recovery or injury management intervention is to look at the harm – will this process cause harm or not?" says Dripps.

"Cupping is one of those tools that some people find beneficial, like dry needling or certain types of massage."

"Really, it comes down to an individual working with a qualified professional to find what's the best recovery intervention for them – just because an elite athlete like Phelps uses cupping, doesn’t mean you'll automatically become a great swimmer if you try it yourself."